INHIBITING CORROSION IN CRUDE-OIL DISTILLATION UNITS BY HETEROCYCLIC-COMPOUNDS

The behaviour of 3-amino-1,2,4-triazole (ATR) 2-amino-thiazole (ATH) and one commercial mixture (H-1) as corrosion inhibitors for carbon steel exposed to export grade Kuwaiti crude oil was studied in a crude oil distillation pilot plant (DISTOP 100) using ammonia gas as a neutralizing agent. The results show that the presence of 10 ppm of (ATR) or (ATH) decreased the corrosion rate of carbon steel by >90%. However, the commercial inhibitor (H-1) inhibited the corrosion of carbon steel by 84% under the same experimental conditions. X-ray photoelectron spectroscopy showed that the corrosion inhibition of carbon steel by (ATR) or (ATH) is attributed to the formation of iron complex layer compounds on the metal surface. SEM micrograph of the surfaces of the specimens tested in the presence of (ATR) or (ATH) showed the formation of a relatively smooth thin film, free from localized areas of attack compared to the blank specimen.